Apparatus for continuous production of soap



Dec. 13, 1955 F. 1... LACHAMPT APPARATUS FOR CONTINUOUS PRODUCTION OFSOAP 4 Sheets-Sheet 1 Original Filed Sept. 13, 1949 05k qumh E6 .256 QwlRIDPQR/ WEIGHT PER CENT ATTORNEYS Dec. 13, 1955 F. L. LACHAMPT 2,726,937

APPARATUS FOR CONTINUOUS PRODUCTION OF SOAP Original Filed Sept. 1.5.1949 4 Sheets-Sheet 2 I d- Q I 0 I A Q \l o 3 S g 2 2 N 8 9, R "3 Q Pgo) E o a 8 k a K) ga 12 rl Loy I k H 6 i3 0 I Q L g N '2 1- 2 I I I I II I I o :2 a s a a 3 3 a 2 c/ V0.9 .ZNJJ 8.7a .ZHQ/JM INVENTOR,EL.Lad2aIIy2Z;

ATTORNEYS Dec. 13, 1955 F. 1.. LACHAMPT 2,726,937

APPARATUS FOR CONTINUOUS PRODUCTION OF SOAP Original Filed Sept. 13,1949 4 Sheets-Sheet 3 wnaauzmio 4 ALKALINE LYE PURE WATER HEATEDTHERMDSTAT 7 2 ll SOAP 83 OTOR MIXING CHAMBER DECANTATIDN CHAMBER 43MOTOR 50 IXING CHAMBER GENIZER 82 18 81 60 25 R Z6 4, MIXING CHAMBERREACTION CHAMBER 2 29 DECA NTATION 28 CHAM BER MIXING CHAMBER 7 nacmmlouZ9 CHAMBER MOTOR SWITCH HEATERS CHAMBER 9 INVENTOR P ,F1..LamanpL,

BY WfM+M ATTORNEYS Dec. 13, 1955 F. L. LACHAMPT 2,726,937

APPARATUS FOR CONTINUOUS PRODUCTION OF SOAP Original Filed Sept. 13.1949 4 Sheets-Sheet 4 ATTORNEYS United States Patent 2,726,937 APPARATUSFOR CONTINUOUS PRODUCTION OF SOAP Felix Lucien Lachampt, Franconville,France, assignor to Union Frangaise Commerciale ct Industrielle,Casablanca, Morocco, a corporation of Morocco Original applicationSeptember 13, 1949, Serial No. 115,536. Divided and this applicationApril 19, 1951, Serial No. 221,789

4 Claims. (Cl. 23260) This application is a division of my applicationSerial No. 115,536, filed September 13, 1949, entitled Method andApparatus for Continuous Production of Soap, now abandoned.

The invention relates to an apparatus for obtaining the continuoussaponification of fatty materials by an alkaline lye, particularlyglycerides by a caustic solution, to obtain directly a saponified massin the neat phase, as defined particularly by McBain and Lee in theirstudy Application of the phase rule to soap boiling published inIndustrial and Engineering Chemistry in August 1942, pages 917 to 921.

An object of my invention is to provide an apparatus for producing asubstantially neutral soap.

A further object of the invention is to provide an apparatus forsaponifying washing and purifying continuously a soap obtained directlyin its neat condition.

According to the invention an alkaline lye having a concentration chosenas indicated below and a quantity of fatty material are mixed in acertain proportion so that the soap obtained has a free alkali contentabove 0.01% and preferably about 0.1%. An emulsion of the type water inoil is formed from the alkaline lye at about room temperature andpreferably around 20 C. with the fatty materials at a temperatureslightly above such as 2 C. above their melting temperature. Thetemperature of the fatty materials should be at least 20 C. Thisemulsion is dispersed and formed in less than seconds, generally in 3seconds, so that the droplets of dispersed caustic lye have a diameterof less than 2 microns at the outlet of the emulsifying apparatus. Thedispersed emulsion flows by gravity into a saponification chamber undersubstantially atmospheric pressure and such chamber is maintained at aconstant temperature between about 85 and 95 C., preferably at 90 C.where it is transformed into a saponified mass in the neat phase. Thistransformation is elfected at a linear speed of 3 cm./minute at the hotpoint in the chamber maintained at 90 C. It takes place practically inless than 3 minutes.

An object of the invention is also the purification of the soap soobtained. For this purpose there is a first continuous washing of theneat soap by circulating in countercurrent a solution of sodium chloridewhose concentration is selected as specified below. After mixing, morethan 90% of this solution separates in less than 10 minutes by gravityalone which results in the elimination of the larger portion of theglycerine and impurities. Then a second washing of the soap is carriedout with a caustic solution at a limit concentration defined below whichgives after mixing and separation by gravity a soap free from sodiumchloride and slightlyalkaline. This soap is neutralized by mixing itwith a fatty acid or with a neutral fat which reacts rapidly.

The saponification arrangement in accordance with the invention, inaddition to means for distributing the fatty materials and alkaline lyeunder the conditions of temperature and in the desired proportions,comprises essentially:

1. An emulsifying or homogenizing apparatus fed by the distributionmeans designed to provide in less than 10 seconds, generally in 3seconds or less, an emulsion in which the dispersed droplets of lye atthe outlet of the apparatus have a dimension below 2 microns.

2. A reaction chamber with means for maintaining its temperatureconstant between and G, into which the emulsion formed by the emulsifierpasses.

3. A receiving kettle for the saponified mass provided with an agitatorand means for maintaining the temperature constant between 85 and 95 C.

The saponification arrangement outlined above develops a totallysaponified mass in less than 5 minutes starting from the fats.

The washing arrangement disclosed herein comprises two groups ofsuperposed washing stages with the soap circulating from bottom to topand the washing solution used in each group from top to bottom of thegroup. Each group is formed of several superposed stages which have aninlet for the soap and an outlet for the washing solution to the lowerstage, an outlet for the soap and an inlet for the washing solution tothe upper stage and means for circulating the soap from bottom to topand the washing solution from top to bottom across each stage. Thecirculation means includes a mixer connected to a soap inlet and to awashing solution inlet, and a decantation tank connected to the outletfrom the mixer for receiving the soap mixed with the washing solution.

The neutralization arrangement is connected to the upper portion of thewashing arrangement to receive the soap which is deglycerinated and freefrom impurities. It comprises a mixer into which the soap enters and aninlet conduit for the fatty body for the neutralization (fats, fattyacids).

The assembly of the washing and the neutralization arrangementscomprises furthermore means for maintaining a constant temperaturebetween 85 and 95 C. and this is generally accomplished as for thesaponification step, by water maintained at a constanttemperaturecirculating in a double walled casing.

With the above and other objects in view which will become apparent fromthe detailed description below one method and apparatus for carrying outthe invention, which is not to be construed in a limiting sense, isshown in the drawings in which:

Fig. 1 shows a diagram explaining the conditions of equilibrium of thephases of sodium stearate with a sodiurn chloride solution of variousconcentrations,

Zshows a similar diagram for a fat mixture comprising 25% coconut oiland 75% tallow mixed with solutions of sodium chloride of variousconcentrations,

Fig. 3 is a diagrammatic view illustrating a saponification, washing andneutralizing apparatus, v

Fig. 4 is a vertical sectional view with parts in elevation and cut awayillustrating a type of homogenizer which may be used, and

Fig. 5 is a partial horizontal cross-sectional view on section line 55of Fig. 4.

In the various figures. similar reference characters indicate likeparts.

The process of the invention carried out by the apparatus comprisesthree distinct phases: saponification, washingof the soap obtained, andthen its neutralization.

An essential feature of the invention is to obtain im mediately a soapin the neat phase. This requires the.

- v caustic concentration to be such that there is formed an emulsion ofthe type water-in-oil.

For defining clearly the conditions of operation, reference is made toFig. 1, showing the diagram of McBain and Lee. This diagram illustratesthe conditions of equilibrium of the phases of sodium stearate with asodiin solutions of sodium chloride having varying concentrations. 7

The practical application. of saponifying quickly fatty substances byemulsitication with an alkaline lye presents a number of difficultieswhich have not. been overcome heretofore. The factors which control arapid and complete saponification are the following: the quantity andthe concentration of the caustic soda lye, the temperature of the fattysubstances and the lye, the type of the emulsion,. the manner ofpreparation of the emulsion, andv the degree. of dispersion and themanner of bringing about the reaction in order to avoid a separation ofthe emulsion.

The concentration of the caustic soda should be such that an emulsion ofthe type water-in-oil is formed and the quantity of the caustic sodashould. be siightly in excess of the theoretic quantity necessary forsecuring a complete saponification of the fatty materials. An excess ofcaustic soda from 1 to 5% gives good results and such excess is usuallypreferably between 1 and 2%.

In industrial soap the content offatty acids in the neat phase is.generally between 60 and 65%. The. concentration of soda lye to be usedin the present process should be selected by taking account of thesaponification index of the fatty materials and their content of freefatty acids. When there are no free fatty acids present theconcentration of the soda lye should not go below 33 and maybe up to40%.

There is indicated upon the table below the concentrations that the sodalye should have according to .the saponification index and the contentof free fatty acids in the fats to be saponified.

Sapouificatton index 182 196 I 210 i 224 238 252 Percentage of sodacorresponding 13 14. 15. 16' 17 18 Concentration of Soda Lye Percentageof Free Fatty Acids:

The table above shows that the concentration of caustie soda lye shouldincrease as the saponification index increases while it should diminishas the content of free fatty acids increases. In certain particularcases it is necessary that the concentration of the soda lye should goto p The temperature of the'fatty substances must be at least 20 C.Generally, the temperature must be higher Percent of free fatty acids:Temperature, C;

0 4o 5 so -48 51 100 55 The emulsion must be prepared and dispersed tothe proper degree, that is the diameter of droplets of lye dispersed infatty materials should be less than 2 microns. The dispersion of themixture of fatty bodies and alkaline lye should take place in a veryshort time, less than 10 seconds, and practically it generally takesplace in. 3 seconds for the following reasons: If no free fatty acidsare present in a. fatty substance, the emulsion obtained remains in. aliquid condition for some minutes. If, however, the content in freefatty acids is increased in the fatty substances, the emulsion mayhardei1" quickly and therefore the. emulsion must be. drawn quickly fromthe homogenizing apparatus. Thus, in the case of dispersions containingdroplets of lye having a size less than 2 microns, the reaction sets inafter starting at a fore the most suitable type of homogenizer for,carrying out the invention comprises a pair of closely spaced-panallelsurfaces displaced with a high tangential speed relative toone another,such surfaces dispersing and throwing out the emulsion, which is causedto flow into a reaction chamber maintained at a temperature between 85."and 95 C. Due tothe quick propagation of the reaction, nodanger is to befeared of a fbreaking of the emulsion under such conditions.

The soap in neat phase, that. is obtained by carrying out'thesaponification conditions of the process according to the presentinvention, as. indicatedabove, must frequently for commercial usage bedeglycerinated and. purified. in order to eliminate the protein.materials from the fats and the soaps of oxidated acids. as. well asotherimpurities.

The saponified I a. solution of sodium chloride, and then withaQsolution of. soda lye NaOI-I), the concentrations of. said solutionsbeing chosen in. such a Way that, the neat. soap, after- 7 having beenmixed. with such solutions, separates by gravity while. remaining still.in its neat. phase.

Herein the term limit" lye or limit washing solution" fora neat soapmeans a solution, of sodium chloride or a solution of caustic soda or amixture. of these two solutions in any proportions whatsoever, having aconcentration such that when mixed with. soap in the neat phase, thesoap separates entirely from. such washing solution without beingdissolved thereby while a solution of a. slightly lower concentration.than such limit concentration would dissolve this same soap. In otherwords. the washing solution: after its mixture with the neat soap andseparation from the neat soap takes a concentration equal to the limitconcentration. It may also be said that a washing solution having avconcentration below such minimum or limit" lye will dissolve a portionof the soap when it is placed in the presence of'neat soap, thus givinga mixture of neat soap and nigre. Y Referring to the diagrams of Fig. 1and Fig. 2 relative to the equilibrium of the phases of a soap in thepresence of a solution of sodium chloride; the concentration of thelimit lye corresponds to the point L. This concentration can be easilyobtained byv test since. it is a well defined physicochemical constantfor each soap or mixture of soaps. p

The equilibrium diagrams of a soap, in the presence of a solution ofcaustic. soda or a mixture of a solution of sodium chloride and asolution of caustic soda have an analogous form to that shown upon Figs.1 and 2.

Inpractice the washing operations are carried out with awashing solutionin equilibrium with the neatsoap having a concentration between thepoints L and G. As a matter offact, it is seen from the diagrams that asolution having the G concentration remains in equilibrium with neatsoap and kettle wax simultaneousiy. If a solution having a concentrationhigher. than defined by the point G in the diagrams is used, however,the neatsoap granulates, that is becomes kettle wax. The. choice massin. its neat phase is washed with of a suitable concentration for thewashing solution is an important feature of the invention, since suchchoice permits securing a quick washing of the neat soap, and itsseparation from the washing solution by gravity alone. If a washingsolution having too high a concentration should be used, on thecontrary, a granulated soap in the kettle wax phase would be obtained,which would retain some or all of the solution and would require theapplication of centrifugal action to be separated from the retainedportion of the solution. Moreover, the elimination of impurities is farless complete.

Thus washing solutions are chosen, having concentrations between theconcentration of the minimum lye or limit lye and 1.15 times suchconcentration. Under such conditions, the washing solution remains inequilibrium with the neat soap and a complete separation is obtained bygravity alone in a time less than minutes. v

The concentration of the minimum or limit lye may be determined byexperiment. and one part of a washing solution, such as a brine, areplaced in small beakers in a water bath. In each beaker a solutionhaving a known concentration different from the concentration of thesolutions in the other beakers is placed. The mixtures in the beakersare stirred, and that washing solution is chosen, which does notdissolve the soap, and which has a concentration slightly greater thanthat solution in the series in which some of the neat soap is dissolved.

The improved method and an apparatus for carrying the same into effectwill now be described.

An alkaline lye is prepared, having the limit concentration, ashereabove defined, and is mixed with fatty substances, in such an amountthat the proportions of fatty acids, alkali and water, respectively,correspond with the stoichiometric proportions for the desired neatsoap. More specifically, an alkaline lye at room temperature, preferablyabout C., is emulsified with a fatty substance having a temperaturesligl'rtly greater than the melting point thereof, by 2 C., forinstance, an emulsion of the type water in oil is produced and dispersedrapidly, in such a way that the suspended droplets of lye have a sizeless than two (2) microns, when flowing out from the emulsifyingapparatus. The dispersed emulsion is circulated in a chamber keptsubstan tially at atmospheric pressure and whose walls are heated to aconstant temperature within the range 85 C. to 95 C., say 90 C., wherebyan almost instantaneous saponification occurs giving a saponified massin its neat phase.

in a preferred modification of the method, the amount of alkali is madegreater than the quantity required for a complete saponification by 1%to 2%, the neat soap thus obtained being slightly alkaline containing0.01 to 0.1% alkali when the soap is washed. The neat soap is subjectedto a first washing operation by counter-flowing a solution of sodiumchloride having a concentration which is in equilibrium with the neatsoap. In this manner the major portion of glycerine and impurities areseparated by gravity only. Then the soap is washed in counter-flow by asolution of caustic soda, having a concentration in equilibrium with theneat soap when intimately mixed therewith, whereby a soap without anysodium chloride is obtained and which is slightly alkaline. This soap isthen neutralized by mixing with a neutral fatty acid, which issaponified rapidly by the alkali present in excess in the neat soap. Orthe soap is mixed with a substance of any well-known type acting as abuffer enabling the pH value of the soap to be kept near the neutralvalue.

An apparatus for carrying out the above-mentioned method comprises incombination saponification, washing and neutralizing devices, as will beexplained below in fuller detail: p

"The saponification arrangement comprises in combina- Two parts of neatsoap a tion, means for supplying fatty substances and alkaline lyerespectively having the required temperature and proportion conditions.An emulsifying apparatus is fed from the above-mentioned means and isadapted to produce an emulsion of the type water in oil within a periodof less than one minute and preferably some seconds. Upon flowing fromthe emulsifying apparatus, the emulsion contains dispersed droplets oflye whose size is less than two (2) microns and preferably below 1micron. The arrangement further comprises a reaction chamber fed fromthe emulsifying apparatus and means associated with the reaction chamberfor maintaining the inner temperature thereof at a constant valuebetween and C. There is provided a receiving tank or kettle for thesaponified mass, provided with stirrer means and with means formaintaining a constant temperature between 85 and 95 C. therein.

Such a saponification arrangement enables a saponified and glycerinatedmass to be obtained, which may be subjected to further well-knownoperations, such as the addition of perfumes, super-fatters,pharmaceutical products, or molding or chilling for immediate use.

The washing arrangement following the above described saponiiicationcomprises in combination two series of superposed washing stages, meansfor causing the soap to flow upwardly from the lowermost stage, andmeans in each series for flowing the related washing solution downwardlyfrom the uppermost washing stage in the series. Each of said seriesincludes a plurality of superpose washing stages and includes means forfeeding soap to, and drawing off the washing solution from the lowermoststage in the series, means for circulating the soap and the washingsolution through said stages in reverse directions with respect to eachother, and means for drawing oif soap from, and feeding washing solutionto the upper-. most stage of the series. series comprises a mixer, aninput pipe for soap connected thereto, an input pipe for washingsolution also connected thereto, and a decantation tank or kettle fedfrom said mixer in the related stage for receiving the mixture of soapwith washing solution for decantation therein.

The neutralizing agent is connected to the upper end of the washingarrangement and receives therefrom a neat soap free from glycerine andimpurities. The neutralizing arrangement comprises a mixer, means forfeeding soap to such mixer and means for feeding a neutralizingsubstance to the mixer, such as a fat, a fatty acid or any well-knownbuffer composition.

The neutralizing arrangement also comprises means for maintaining aconstant temperature therein within the range of 85 to 95 C. Preferably,such means include means for circulating water at constant temperaturein a double outer wall, and similar means are used preferably in thesaponification arrangement for heating the reaction chamber and thereceiving tank thereof.

Preferably the emulsifying and homogenizing apparatus comprises avertically arranged, cylindrical housing having a vertical shaftjournaled for rotation at its opposite upper and lower ends,respectively, said shaft extending along the vertical axis of thehousing. At its lower end, the shaft carries a frustroconical discmember having an under surface of greater area than the upper surfacethereof, the frustroconical surface of the disc member is housed in acasing of similar shape secured to the lower end of the housing, andcontrol members are provided for varying the gap between the outer andinner frustroconical surfaces of the casing and the disc member,respectively;

The frustroconical surfaces are rotated relative to each other. Helicalgrooves are cut or formed in the discholding shaft, and driving meansare provided for rotating said shaft with a speed amounting to manythousands R. P. M. in such a direction that said helical grooves imparta downwardly directed movement to a fluid mass in the housing. Also, acylinder coaxial with the shaft 3 and the housing is made of perforatedsheet metal and Finally, each stage in each is secured to the uppersurface. of the frustroconical disc member to be rotated. therewith. Onthe. other hand, the enclosing housing supports a coaxially arrangedcylinder made of perforated sheet metal and coaxially mounted Within thefirst-mentioned rotatable cylinder and closely spaced therefrom. Therotatable cylinder is given as 7 great a diameter'as possible, and thusextends closely to the innerwall of the enclosing housing. The fattysubstances and the lye are fed between the enclosing housing and therotatable cylinder. In this manner these substances are squeezed throughthe fixed'and rotatable perforated cylinders andare driven downwardlythereafter by the helical grooves in the axial shaft. Then bothsubstances are further emulsified and dispersed betweenthefrustroconi'cal surfaces of the disc member and the casing respectively,whose spacing is controlled to obtain dispersed droplets. of lye in thefatty substance with a diameter between .5 and 2' microns.

' Preferably, the reaction chamber is in the shape of a vertical annularring having a casing extending along its vertical axis and surrounded bya double outer wall coaxial with the casing and communicating therewith.Hot water is fed through the central casing and the outer double wall ata temperature within the range 85 to 95" C., thus maintaining thedesired temperature within the reaction chamber.

The invention will be better understood from the following detaileddescription of an embodiment for illustration purposes only, and notconstituting any limitation thereof, in connection with Figs. 3, 4 and5.

There'is shown diagrammatically upon Fig. 3 an apparatus for thesaponification, for the washing and for the neutralization of the soap.

The fats are stored in a reservoir 1 from which they are fed to a tank 2by a pump 3. The tank 2 preferably has a capacity corresponding to aboutthe consumption of fats for a ninety minute operation of the apparatus.The tank 2 has an overflow pipe 4 which returns excess fats in tank 2 tothe reservoir 1. A heating arrangement 5, shown schematically, iscontrolled by a valve 6 which is in turn controlled by a thermostaticdevice 7. The alkaline lye is stored in a reservoir 8 and is fed to atank 9 by a pump 10. The tank 9 is also designed to hold a supplyallowing the operation of the installation for about ninety minutes.flow pipe 11 which returns excess lye to the reservoir 8. The tank 9 is.provided with heating means 12 under the control of a thermostat 13 anda heating regulating valve 14'.

The fats are withdrawn from the tank 2 by a pump 15 through a pipe 16and led bya pipe 17' into the homogenizer 18. The alkaline lye is drawnfrom the tank 9 through a pipe 19 by a pump 29 and then into a pipe 21which leads to the homogenizer or emulsifier 18.

'Both pumps 15 andf are of the variable flow type, and in thismanner therelative proportions of flow of fats and alkaline lye, respectively, maybe maintained to the desired value with a maximum variation of the orderof 1%. Preferably the pumps 15 and 20 are of the variable flowvolumetric type including a very strongly built plunger piston.Preferably also both pumps 15 and 20 are driven from a common motor 22so that stopping of one pump only is prevented, which would bedetrimental to the correct relative proportions of both components. Itis-necessary that the pumps 15 and 26 be provided with suitablefiltration devices, in order that no grit may pass therethrough, whichwould hinder the operation of the valves and also a pressure head willbe. applied to said pumps by spacing them under the. related tanks 2 and9 at least one meter. Finally, the. flow through the pumps. 3 and It ismaintained greater than the flow through the pumps 15. and 29,.respectively so that; fats and alkaline lye. will overflow at all timesin the overflow pipes 4 and 11, respectively,

It has an overand in this manner the fats will be stirred continuouslyin the reservoir 1 and in the tank 2, while the alkaline a slightlyalkaline neat soap.

lye will be stirred continuously in the reservoir 8 and in the tank 9.

The homogenizing apparatus 18 will be described below in fuller detail.This apparatus is arranged at the upper end of a vertical reactionchamber 23 comprising a cylindrical interior casing 24 and a coaxialouter double walled casing 25, 26, the interior of which communicateswith the interior of the casing 24 by means of tubes 27 and 28. Thereaction chamber proper is formed by the annular space 29 between thecasing 24 and the inner wall and the emulsion from the homogenizingapparatus 18 is projected into this annular space.

The chamber 29 communicates at its lower end With a cylindrical-conicalkettle 30 having a double outer wall 31, 32 connected with the casing 24through a pipe 133. A stirring apparatus 33 is provided having a drivingshaft 34 journalled in the kettle 30 and comprises frames 35, 36provided with arm extensions. This as sembly is rotated by a drivingmechanism (not shown). A shutter 37 is adapted to be swung about its end38 by means of a handwheel 39 fixed to a screw arrangement. Aninspection hole 40 is closed by a transparent plate, and the descent ofthe saponified mass from the chamber 29 on the shutter 37 may beobserved through such trans parent plate.

The saponified mass is evacuated at the bottom end 7 of the kettle 30 bya variable flow volumetric pump 41 which feeds the mass through a pipe42 into a washing tower 43 having a double walled casing 44, 45. A pipe46 feeds the sodium chloride solution to a variable flow volumetric pump47 which forces it through a pipe 48 into the tower 43. I

A pump 50 supplied with lye from tank 9 through pipe 52 forces the lyethrough the pipe 49 into tower 43 and water is also supplied to pipe 49by a pump 51. These two pumps have an adjustable volumetric flow. Wateris fed to the pump by pipe 53 from a tank54.

The tank 54 is provided with heating means 55 such as a steam coil forexample with a thermostat 56 controlling a valve 57. A pipe 61 at thebottom of the tower 43 communicating with the interior of the doublewalled casing 44, 45 supplies the water circulating therein to a pumpwhich forces it through pipe 58 to the interior of the double walls ofkettle 30. From here the water passes by pipe 133 to casing 24 andbetween walls 25 and 26- to pipe 62 to tank 54 from which it leaves by apipe 63 into the annular space 64 surrounding a mixer 65.

The mixer 65 is provided with horizontal arms 66 and its vertical shaft67 rotates in the upper portion of the tower 43. The mixer 65 is drivenby a motor 68. The pipe 69 constitutes a discharge tube for the washedand neutralized soap and a storage tank 70 is provided for such soapfrom which it may be supplied to various conventional finishingoperations of known type not shown;

A tank 71 contains a neutralizing substance for a This substance may bea fatty acid, a neutral fat, a buifer mixture or an ester of a fattyacid, for example. The neutralizing substance is fed to the mixer 65through a pipe 72 from a variable flow, volumetric pump 73 which isitself fed by a pipe 74 from tank 71. Heating means 75 is provided forthe tank 71 controlled by a thermostatic device 76 controlling a valve77. Y

The tower 43 has five washing stages ofwhich three washing stages arefor washing the soap with a sodium chloride solution, and two washingstages are for washing the soap with an alkaline lye. Each washing stagecomprises a mixer 78 having a horizontally extending shaft V v Id 79driven by a motor 80. Each mixer 78 com unicates.

with a. decantation tank 81 immediately below the mixer.

concerned by a tubing 82 to supply the mixed product to such decantationtank. The soap passes from each decantation tank 81 to the mixer 78 inthe next upper stage through a pipe 83. The washing lye used in the twouppermost stages of the tower 43 is drawn off through a pipe 85. Thesodium chloride solution used is drawn off from the tower 43 through apipe 86.

The washing solution is fed from a decanting tank 81 to the mixer 78 ofthe stage immediately thereunder by means of a variable flow, volumetricpumps as indicated at 87, 88 and 89.

A pair of float members 90 are provided, each having a specific gravitybetween the specific gravity of the washing solution and the specificgravity of the washed soap in the related stage. The float members 90are arranged in the lowermost Washing stage for the sodium chloridesolution and in the lowermost washing stage for the alkaline lyesolution, respectively. Each float 90 oscillates a lever 92 about arelated axis 91. The levers 92 each control a switch 93 for supplyingcurrent to an electric motor 94 for opening or closing a valve 95.

The emulsifying apparatus 18 (Figs. 4 and comprises a housing 96 forminga cylindrical chamber 97. The housing 96 has a threaded portion 98, acylindrical portion 99 of restricted diameter and a frustoconicalportion 100. The various elements are carefully machined to accuratelypredetermined dimensions. Reinforcing ribs 101 are provided between theupper flange 102 and the lower flange 103 of the housing. A hub-carrier104 in the shape of a wheel, with radially projecting arms and a centralsolid portion is attached to the lower flange 103 and coaxiallytherewith by any suitable means such as countersunk screws 105 screwedpartly in the bore of the flange 103 and partly in the outer cylindricalsurface of the member 104. The members 103 and 194 are tightly fittedtogether. An enlarged portion 166 is formed in the housing 96 with acylindrical duct 107 therethrough having a transverse partition 108therein. The duct 107 is connected with the pipe 17' at one end, andwith the pipe 21 at the other end thereof, for feeding fatty substancesand alkaline lye, respectively, into the cylindrical chamber 97.

An upper hub 109 contains the races for the two conical roller bearings110. The hub 109 is exteriorly threaded to fit the threading 98 in thehousing 96. The hub 109 also is formed with teeth 111 which mesh with apinion 112 rotatively mounted on a shaft 113 supported from a supportfixed to the flange 102. The pinion 112 is integrally connected with ahelical gear 114 meshing with a worm gear 115 which may be rotated by ahand-wheel 116 fixed to the shaft carrying gear 115.

A metal cylinder 117 provided with perforations 118 is attached to thehub 109 by any suitable means. Packings 119 and 120 prevent emulsion andgrease from being projected.

The rotating elements in the emulsifying machine are mounted on a shaft121 having an upper end 122 of square cross-section for driving theshaft 121 by an elastic clutch member 123. The shaft 121 is journalledin the bearings 110 at its upper end and in a ball bearing 124 at thelower end thereof. The ball bearing 124 is slidable axially in a recess125 provided in the lower hub 104. A helical thread forming a helicalgroove 126 is formed on the shaft 121 and a frustoconical plate 127 iskeyed to the shaft 121 at the lower end. The outer periphery of theplate 127 corresponds to that of the frustoconical portion 100 formed inthe housing 96.

The arrangement described allows, by turning the wheel 116, to establisha desired spacing between the truncated conical surface 100 ofthe'housing and the truncated conical surface of the plate 127. Arotation of the upper hub 109 causes the assembly of elements carried bythe shaft 121 to ascend or descend.

A cylinder 128 is secured coaxially to the plate 127, at the uppersurface thereof, by any suitable means. This cylinder 128 is made ofsheet-metal and provided with perforations 129. The outer diameter ofthe cylinder-128 is positioned as close as possible to the housing atthe restricted portion 99.

A motor 59 (see Fig. 3) is provided with a driving shaft 130 and ismounted on a platform 131 by means of bolts 132.

The following example illustrates how the method may be carried out byusing the above described arrangement. It is assumed in such examplethat a neat soap is to be produced starting from a mixture of fatsincluding 75% tallow and 25% coconut oil, said mixture having a contentof free fatty acids equal to 20% and having a saponification index of210.

The fats are maintained in the tank 2 at a constant temperature of about47 C. Preferably the reservoir 1 and the tank 2 are made of a metalwhich does not react with the fats so that no color is given to thestored fats from the metal of the tanks. For instance, use may be madeof stainless steel or aluminum for reservoir 1 and the tank 2. Thecaustic soda lye is kept at a 20 C. temperature due to the automatictemperature control arrangement described. The soda concentration ischosen equal to 29%, as given by Table 1 above which indicates theconcentration of lye to be used depending on the saponification indexand the fatty acid content of the used fat.

100 parts by weight of the fat mixture, and 52.3 parts by weight of thecaustic soda lye at a 29% concentration are fed simultaneously to thechamber 97 through the pipes 17 and 21, respectively. Both productsenter the emulsifying machine through the parts 107. The shaft 121 ofthe emulsifying machine is rotated with a speed of about 3,000 R. P. M.,and in such direction that the helical groove 126 in the shaft 121drives the mixture towards the frustoconical plate 127. This mixture hasbeen squeezed first between the fixed cylinder 117 and the rotatingcylinder 128. The spacing between the frustoconical surfaces 100 and 127has'been adjusted to give a clearance amounting to a few hundredths of amillimeter. A device of well-known type, including a micrometric screw(not shown) is used, and is attached to the handwheel 116 forcontrolling accurately the position of the plate 127. In one particularembodiment, the plate 127 had a diameter of 32 centimeters, and theperipheral speed of the plate 127 amounted to about 50 meters persecond. At the output end of the homogenizing machine 18, an emulsion isobtained in which the droplets of lye dispersed in the fatty substanceshave a size within .5 and 2 microns, while the mixture passes throughthe apparatus in less than 3 seconds. Obviously any other apparatusgiving the same results in a correspondingly short time could be usedinstead of the described apparatus.

The emulsion obtained passes into the reaction chamber 23 and throughthe annular space 29, the distance between the casing 24 and the innerwall 25 being 6 cm. The heating water circulated at a constanttemperature of about C. by the pump 60 through the double walled casingsof the kettle 30 and the chamber 23 maintains the chamber 23 at atemperature favorable for the beginning of the reaction.

The shutter 37 is used for reducing the rate of falling of the soap,which is observed by a worker through the inspection opening 40 by meansof a convenient lighting arrangement (not shown) arranged within thechamber. Care is .taken that the reaction chamber 23 is maintained atleast half filled. The shutter 37 also acts as a hydraulic jointpreventing the entry of air into the reaction chamber 23, since thepressure within the reac-' tion chamber 23 substantially equalsatmospheric pressure. The shutter 37 is maintained normally in a substantially constant position and is only displaced slightlyWhentheyiscosity of the soap changes.

The reaction may be started also by projecting dry gra es?" 11 steamunder the frustroconical plate 127.- Suchan; arrangement; however,requires that water be circulated around the reaction chamber 23 inorderto. maintain the temperature thereof at a constant value since thesaponification reaction is greatly exothermic and any boiling must beavoided. The reaction, when started,

proceeds to completion without needing any external. heat. Theemulsionpreliminarily whitish is transformed in the mixer 78- in thethird washing stage by means of the variable flow, volumetric pump 47,ina proportion of 76.15 parts inweight for 1 52.3 parts in Weight ofsoap introduced in the mixer 78 in the lowermost washing stage.

The" washing solution decanted in the decantationtanks 81 successivelypasses through the stages under the action of the variable 'flow',volumetric pumps 87 and 88-, respectively. The flow through such pumpsis so con.- trolled as to be slightly higher than the flow throughthepump 47", and amounts to about 80 parts by weight.

Thus the soap and the sodium chloride solution are passed through thewashing stages in countenflow. The products are mixed in the mixer 78 ineach stage, then the mixture is decanted in the decantation tank 81- inthe same stage,then the washing solution passes to the next lower stageand the soap passes to the next upper stage. The washing'solutionremovesglycerides and impurities from the soap.

The brine containing glycerine and impuritieswhich separates in thedecantation tank 81- in the lowermost washing stage is drawn elfautomatically through the pipe 86, the valve 95 of which is controlledby the float device 90. The control of the valve 95 may beof anywell-known electrical or pneumatic type. When drawn fromthe lowermostdecantation tank 81', the brine contains 9.12% NaCl and 0.19% NaOH.

The washed soap, when flowing out from the third washing stage in thetower 43', contains still a certain amount of salt. Its compositionamounts to about'64% fatty acids and .7% salt. In order to eliminate thesalt, the. soap is then washed in both upper stages in the tower 43 bymeans of a caustic soda solution of a concentration containing NaOH byweight. The soap is. not dissolved by such a solution. As for the NaClsolution, occluded gases. are removed thoroughly from the caustic sodasolution.

The washing lye is fed. to the tower 43 by means of the combined actionof the variable flow, volumetric. pumps 59 and 51. The concentrated lyeis taken at a temperature of C. and mixed with pure water at atemperature of 90 C. to give the washing solution. The temperatures ofthis mixture, however, is maintained at 90 (1., due to the fact that theconcentrated brine becomes diluted in water while supplying dilutionheat.

The soap and washing lye pass through the tower in counter-flow, as inthe lower stages. The used washing lye is taken from the decantationtank in the fourth stage in the tower (from the bottom of said tank), bythe action of a float device 90 similar to the device 90 for thelowermost stage in the tower.

Care is taken that a pressure slightly greater than atmospheric pressureexistsv in the various washing stages, whereby any penetration of air isavoided.

The soap washed with the. caustic soda solution, when flowing into themixer 65', has an almost zero content l2 of glycerine. Its salt contentamountstoabout .l-% andits sod'acontent is about .7 73-.

The used washing lye flowing through the. output pipe 86 comprisessubstantially 8.65% NaOH and 1.17% NaCl by weight. I

194.5 parts by weight of soap flowing in the mixer 65" are mixed with7.8 parts by weight of a mixture of distillated fatty acids having asaponification index of 210. These fatty acids are stored in a storagetank 71' at a temperature of 80.C., and flow through a pipe I4 under theaction of a variable flow, volumetric pump 73 inserted therein. ing tothe lower end of the mixer 65 feeds the fatty acids thereinto. Thequantity of fatty acids is determined in such a way, that the. finishedsoap has only the required amount in free alkali. Instead of fattyacids, a neutral fat may be used, since the saponificat-ion occurs veryquickly under the operating conditions.

Finally the finished soapflows through the pipe 69 to the storage tank70 and has the following composition at that time:

Percent Fatty acids 65.2 Saltv .10. Free caustic soda .19-

the arrangement of the washing, stages.

I claim;

1. In, an apparatus of the. class described for the, con tinuousproduction of purified soap, an emulsifying device comprising an outercylindrical housing, a. rotatable shaft coaxial. with said housing,helical grooves extend ing. along the outer cylindrical surface of saidshaft, bearing surfaces for said rotatable shaft adjacent both upper andlower ends of said housing respectively, means to rotate said shaft andcause a screw-like displacement of said helical. grooves. with respectto the bottom of said housing, means to shift said shaft axially in saidhousing, a. frustro-conical plate member coaxial with said shaft securedto the lower end of said shaft, said plate. 'member having an uppersurface, of lesser area than the under surface thereof, afrustrorconical bottom portion in said housing having a. conical surfacewhich is sub.- stantially parallel to the outer surface of said,frustroconical plate member and coaxial therewith, a. fillsl perforated. cylinder secured tov said frustro-conical plate member alongthe periphery of the upper surface thereof to extend, upwardly therefromin close relationship. to the inner diameter of said housing, a secondperforated cyl-. inder coaxial with said first cylinder attached to. theupper wall of. said. housing and spaced within said first cyl; inder ata close distance therefrom and means to. feed. a fat-like material andan aqueous material through the wall of said housing and between theinner surface of said housing and the outer surface of said first perforrated cylinder.

2. An emulsifying machine comprising an outer cylindrical housing, arotatable shaft coaxial with said housing, helical grooves extendingalong the outer cylindrical surface of said shaft, bearing. surfaces forsaid rotatable shaft adjacent both upper and lower ends of said houseres ectively, m n to. r ate said. haft. and caus ascrew-likedisplacement of helical grooves; respect to the bottom of said housing,means to shift said shaft axially in. said housing, a frustro-conicalplate member coaxial with said shaft secured; to. the lower end of saidshaft, said plate member havingan upper sur-' From the pump 73 a pipe'/'=2- lead er surface of said frustro-conical plate member and coaxialtherewith, a first perforated cylinder secured to said frustro-conicalplate member along the periphery of the supper surface thereof to extendupwardly therefrom in close relationship to the inner diameter of saidhousing, a second perforated cylinder coaxial with said first cylinderattached to the upper wall of said housing and spaced within said firstcylinder at a close distance therefrom and means to feed a fat-likematerial and an aqueous material through the wall of said housing andbetween the inner surface of said housing and the outer surface of saidfirst perforated cylinder.

3. In an apparatus of the class described for the continuous productionof purified soap, the combination of an emulsifying device and a washingdevice adapted to saponify and purify soap formed by the reaction of afatty material with aqueous alkali, said emulsifying device comprisingan outer cylindrical housing, a rotatable shaft coaxial with saidhousing, helical grooves extending along the outer cylindrical surfaceof said shaft, bearing surfaces for said rotatable shaft adjacent bothupper and lower ends of said housing, respectively, means to rotate saidshaft and cause a screw-like displacement of said helical grooves withrespect to the bottom of said housing, means to shift said shaft axiallyin said housing, a frustro-conical plate member coaxial with said shaftsecured to the lower end of said shaft, said plate member having anupper surface of lesser area than the under surface thereof, afrustro-conical bottom portion in said housing having a conical surfacewhich is substantially parallel to the outer surface of saidfrustro-conical plate member and coaxial therewith, a first perforatedcylinder secured to said frustro-conical plate member along theperiphery of the upper surface thereof to extend upwardly therefrom inclose relationship to the inner diameter of said housing, a secondperforated cylinder coaxial with said first cylinder attached to theupper wall of said housing and spaced within said first cylinder at aclose distance therefrom and means to feed a fat-like material and anaqueous material through the wall of said housing and between the innersurface of said housing and the outer surface of said first perforatedcylinder, and said washing device comprising a vertical tower havingspaced double walls, means for introducing the fluid soap from saidemulsifying device into said tower, means for introducing a washingliquid into said tower, circulating and mixing means for said fluid soapand said washing fluid, means for settling said washing fluid from saidwashed fluid soap and means to separate said washing fluid and saidwashed fluid soap from said tower.

4. The combination of an emulsifying device and a washing device as setforth in claim 3, wherein said tower is subdivided into a series ofwashing compartments arranged in sequence.

References Cited in the file of this patent UNITED STATES PATENTS362,856 Riviere May 10, 1887 2,150,733 Thurman Mar. 14, 1939 2,192,094Moore Feb. 27, 1940 2,245,536 Thurman June 10, 1941 2,322,791 De BackJune 29, 1943 2,348,855 Scott May 16, 1944 2,362,734 Ward Nov. 14, 19442,375,730 Caldwell et a1. May 8, 1945 2,401,756 Gunther June 11, 19462,452,724 Bradshaw Nov. 2, 1948 2,475,605 Prutton et a]. July 12, 1949

1. IN AN APPARATUS OF THE CLASS DESCRIBED FOR THE CONTINUOUS PRODUCTIONOF PURIFIED SOAP, AN AMULSIFYING DEVICE COMPRISING AN OUTER CYLINDRICALHOUSING, A ROTATABLE SHAFT COAXIAL WITH SAID HOUSING, HELICAL GROOVESEXTENDING ALONG THE OUTER CYLINDRICAL SURFACE OF SAID SHAFT, BEARINGSURFACES FOR SAID ROTATABLE SHAFT ADJACENT BOTH UPPER AND LOWER ENDS OFSAID HOUSING RESPECTIVELY, MEANS TO ROTATE SAID SHAFT AND CAUSE ASCREW-LIKE DISPLACEMENT OF SAID HELICAL GROOVES WITH RESPECT TO THEBOTTOM OF SAID HOUSING, MEANS TO SHIFT SAID SHAFT AXIALLY IN SAIDHOUSING, A FRUSTRO-CONICAL PLATE MEMBER COAXIAL WITH SAID SHAFT SECUREDTO THE LOWER END OF SAID SHAFT, SAID PLATE MEMBER HAVING AN UPPERSURFACE OF LESSER AREA THAN THE UNDER SURFACE THEREOF, A FRUSTO-CONICALBOTTOM PORTION IN SAID HOUSING, HAVING A CONICAL SURFACE WHICH ISSUBSTANTIALLY PARALLEL TO THE OUTER SURFACE OF SAID FRUSTROCONICAL PLATEMEMBER AND COAXIAL THEREWITH, A FIRST PERFORATED CYLINDER SECURED TOSAID FRUSTRO-CONICAL PLATE MEMBER ALONG THE PERIPHERY OF THE UPPERSURFACE THEREOF TO EXTEND UPWARDLY THEREFROM IN CLOSE RELATIONSHIP TOTHE INNER DIAMETER OF SAID HOUSING, A SECOND PERFORATED CYLINDER COAXIALWITH SAID FIRST CYLINDER ATTACHED TO THE UPPER WALL OF SAID HOUSING ANDSPACED WITHIN SAID FIRST CYLINDER AT A CLOSE DISTANCE THEREFROM ANDMEANS TO FEED A FAT-LIKE MATERIAL AND AN AQUEOUS MATERIAL THROUGH THEWALL OF SAID HOUSING AND BETWEEN THE INNER SURFACE OF SAID HOUSING ANDTHE OUTER SURFACE OF SAID FIRST PERFORATED CYLINDER.